1. Field of the Invention
The present invention relates to a camera apparatus and a monitoring system, and more particularly to a camera apparatus, which includes a curved mirror reflecting image light representing an image of a wide view field area toward a prescribed direction and an imaging section for obtaining, as an image, the image light reflected by the curved mirror, capable of obtaining an image of a wide view field area and a system including the same camera apparatus.
2. Description of the Related Art
In many cases, automated teller machines (ATM) for automatically paying/receiving money are installed in a relatively small area within a bank or the like, where money is handled, and therefore there is a high possibility that a criminal activity such as larceny might occur. Accordingly, a place where an ATM is installed is required to be monitored at all times using a monitoring camera.
When monitoring an ATM, it is necessary to monitor the operator and an operation panel of the ATM, i.e., the general vicinity of the ATM must be targeted for monitoring. However, in many cases, ATMs are installed in a relatively small area, and therefore a target for monitoring cannot be sufficiently distanced from the location where a monitoring camera is installed. Therefore, there is a possibility that a view field area for an image obtained by the monitoring camera might be limited. In particular, a monitoring camera using an industrial television (ITV) camera has a problem that an angle α of view which enables monitoring is predetermined by an optical system of the monitoring camera, and therefore part of the target for monitoring is located out of an area defined by the angle of view, i.e., the target for monitoring is partially located in a blind area.
FIG. 9 is a side view showing an area monitored by a monitoring camera using an ITV camera normally used for monitoring an ATM which is installed on a wall above the ATM.
In the example shown in FIG. 9, the monitoring camera is installed such that the operator of the ATM is positioned within the area defined by the angle α of view of the monitoring camera. In this case, an entire image of the ATM operator can be obtained, while there is a blind area represented by angle β in directions in the vicinity of a direction vertically downward from the monitoring camera. Such a blind area cannot be monitored, i.e., an operation panel of the ATM cannot be monitored.
On the other hand, although not shown in the figures, when an installation angle of the monitoring camera is adjusted so as to monitor the operation panel of the ATM, it is not possible to obtain an image of a sufficiently widely ranging area for monitoring the ATM operator.
In the case of monitoring circumstances in a wide range of area around an ATM or the like using a conventional ITV camera, it is conceivable that a monitoring system, which includes a turntable for turning the ITV camera and a driving device or the like for pivotably driving the turntable, is provided so as to allow the ITV camera to be turned pivotably, thereby reducing the blind area created when the ITV camera is used. However, in such a case, it is necessary to provide, in addition to the ITV camera, the turntable for turning the ITV camera and the driving device or the like for pivotably driving the turntable, and therefore the configuration of the monitoring system becomes complicated.
Alternatively, instead of providing the turntable, the driving device, etc., it is conceivable that a wide-angle lens is used to widen a field view area of the ITV camera. However, in such a case, there is a problem in that a large wide-angle lens causes the ITV camera to be increased in size. Further, the ITV camera becomes expensive by the cost of the wide-angle lens.
As an example of a camera apparatus which overcomes the above problems caused by using the conventional ITV camera, there is a vehicle surroundings monitoring apparatus described in Japanese Laid-Open Patent Publication No. 9-118178. This vehicle surroundings monitoring apparatus is applied to a vehicle surroundings recognizing system used for appreciating a positional relationship between a car and an object therearound.
The vehicle surroundings monitoring apparatus described in the above publication includes a wide-angle camera mounted at a left rear end portion of the vehicle and a monitor installed in the vehicle for displaying a view obtained as an image by the wide-angle camera on the screen. The wide-angle camera includes a convex mirror capable of reflecting an omnidirectional view around the vehicle, an imaging device for obtaining a virtual image reflected by the convex mirror, and a transparent pipe for connecting the convex mirror with the imaging device. In the vehicle surroundings monitoring apparatus described in the above publication, the imaging device obtains an omnidirectional virtual image reflected by the convex mirror and a synthetic image is created based on the image obtained by the imaging device so as to allow a positional relationship between the vehicle and an object located therearound, the shape of the vehicle, etc., to be readily appreciated. The synthetic image is displayed on the monitor installed in the vehicle. With such a simple configuration, the vehicle surroundings monitoring apparatus allows easy appreciation of omnidirectional positional relationships around the vehicle.
Further, Japanese Laid-Open Patent Publication No. 2000-206635 discloses a panoramic imaging apparatus including a hyperboloidal convex mirror for reflecting a 360° image, a lens placed so as to be opposed to a reflection surface of the hyperboloidal convex mirror, a camera apparatus for obtaining an annular image reflected by the hyperboloidal convex mirror, and a computer for transforming the annular image obtained by the camera apparatus into a planar image based on a specific viewing angle. With such a simple configuration as to use the computer for transforming the annular image reflected by the hyperboloidal convex mirror into a panoramic image, the panoramic imaging apparatus obtains a panoramic image of a 360° view field area.
In the case of installing a conventional ITV camera in a manner as shown in FIG. 9, it is necessary to confirm whether or not a certain area is appropriately obtained as an image during installation. Specifically, it is necessary to adjust an installation angle, etc., of the ITV camera while viewing an image displayed on a monitor during the installation of the ITV camera, and this is a complicated and time-consuming task.
As in the case described in conjunction with FIG. 9, when using a camera apparatus disclosed in either Japanese Laid-Open Patent Publication No. 9-118178 or 2000-206635 for monitoring a particularly small area in a bank or the like where an ATM or the like is installed, even if the camera apparatus can obtain an image of a wide view field area in a lateral direction, an area in a direction vertically downward from the camera apparatus cannot be obtained as an image since an image of an imaging section of the camera apparatus itself is reflected in a convex mirror of the camera apparatus.
Further, in such a camera apparatus, a device required for controlling an image obtaining operation, e.g., an interface section for transferring an image to an external device, needs to be provided in the vicinity of an imaging device. This increases the size of the imaging section, and thus an area located in a direction vertically downward from the camera apparatus, where obtaining an image is not possible, is also increased. As a matter of course, the device is restricted in its design.
Furthermore, in the vehicle surroundings monitoring apparatus described in Japanese Laid-Open Patent Publication No. 9-118178, the transparent pipe is used for connecting the convex mirror with the imaging device, and in the case of using such a transparent pipe for connecting the convex mirror with the imaging device, when incident light entering into the transparent pipe is transmitted therethrough, internal reflection occurs in the transparent pipe. The internally reflected light reaches the imaging device so that light other than that essentially required is incident on the imaging device. As a result, an image including a plurality of overlapping views is generated.
Further still, the panoramic imaging apparatus described in Japanese Laid-Open Patent Publication No. 2000-206635 does not have a mechanism for maintaining the camera in the state of being opposed to a reflecting surface of the hyperboloidal convex mirror. However, the panoramic imaging apparatus described in this publication is configured to obtain an image by collecting light reflected by the hyperboloidal convex mirror. Although a positional relationship between the hyperboloidal convex mirror and the camera is important in order to obtain a clear and high resolution image, it is difficult to separately install the hyperboloidal convex mirror and the camera in a place where an image obtaining operation is performed, such that the positional relationship between the hyperboloidal convex mirror and the camera is adjusted so as to bring the camera into focus. Moreover, since the panoramic imaging apparatus is intended to obtain an image of a 360° view field area using the hyperboloidal convex mirror, it is appreciated that the panoramic imaging apparatus also uses a transparent pipe so as to hold the hyperboloidal convex mirror and the camera as in a similar manner to the vehicle surroundings monitoring apparatus described in the aforementioned Japanese Laid-Open Patent Publication No. 9-118178. In such a case, as described above with respect to the vehicle surroundings monitoring apparatus described in Japanese Laid-Open Patent Publication No. 9-118178, internal reflection occurs in the transparent pipe and the internally reflected light reaches the imaging device so that light other than that essentially required is incident on the imaging device. As a result, an image including a plurality of overlapping views is generated.